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In order to display the information content of these 51 ensemble rank values, we use a simplified anomaly representation. For this, 7 anomaly categories were defined by the 10^th, 25^th, 40^th, 60^th, 75^th and 90^th percentiles, representing 7 categories from 'Extreme low' to 'Extreme high'. In the forecasts, each of these 7 categories will have a probability value, depending on how many of the 51 ensemble members they contain.

The overall expected anomaly category of the forecast (one of the 7, shown as colour in the map and highlighted in the pop-up table) is defined by the mean of the 51 ensemble member ranks (rank-mean), which represents a robust anomaly value without any random jumpiness. In addition, the uncertainty about these anomalies is also defined using the standard deviation of the 51 ensemble ranks, by their standard deviation (rank-std). Based on this rank standard deviation value, one of three uncertainty categories (low / medium / high) are assigned to the forecast.

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